<!DOCTYPE HTML>
<html>
<head>
    <script type="text/javascript">
        function getnum(){
            var mynode=   document.getElementsByName('myt');
            alert(mynode.length);
        }
    </script>
</head>
<body>
<input name="myt" type="text" value="1">
<input name="myt" type="text" value="2">
<input name="myt" type="text" value="3">
<input name="myt" type="text" value="4">
<input name="myt" type="text" value="5">
<input name="myt" type="text" value="6">

<br />
<input type="button" onclick="getnum()" value="看看有几项？" />
</body>
</html>